The garden's origins can be traced back to 1698 when Frederick III, Prince Elector of Brandenburg donated parts of his hortus medicus to the university in Halle. By 1749 the garden contained 191 plants species. In 1787 it was enlarged to its present size by Karl Christoph von Hoffmann (1735-1801), university chancellor, in response to activities of garden directors Johann Reinhold Forster (1729-1798), who participated in Captain James Cook's second world expedition, and Philipp Jung Hans Caspar (1736-1798). Towards the end of the 18th century many greenhouses were constructed, and by 1825 the garden contained some 7,000 species. Its tropical greenhouse was built in 1872 with the Victoria greenhouse following in 1902. During the 20th century, additional modern green houses were built and old ones renovated, including the 1994 reconstruction of the Victoria greenhouse. The garden grounds also contain the former university observatory, designed by Carl Gotthard Langhans (1732-1808).